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A white flowered mirabilis plant rr was...

A white flowered mirabilis plant rr was vrossed with red coloure RR, If 120 plants produced in `F_(2)` generation. The result would be

A

90 uniformly coloured & 30 white

B

90 Non-uniformly coloured & 30 white

C

60 Non-uniformly coloured & 60 white

D

All coloured & Non white

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem of the flower color inheritance in Mirabilis plants, we will follow these steps: ### Step 1: Understand the Genotypes We have two parent plants: - A white-flowered plant with genotype **rr** (homozygous recessive). - A red-flowered plant with genotype **RR** (homozygous dominant). ### Step 2: Cross the Parent Plants When we cross these two plants (rr x RR), all offspring in the F1 generation will have the genotype **Rr** (heterozygous). According to Mendel's principles, the dominant trait (red flowers) will be expressed in the F1 generation. ### Step 3: Analyze the F1 Generation In the F1 generation, all plants will have red flowers because the red allele (R) is dominant over the white allele (r). Thus, the phenotype of the F1 generation is: - **100% Red Flowers** (Rr). ### Step 4: Self-Pollinate the F1 Generation Next, we self-pollinate the F1 generation (Rr x Rr) to produce the F2 generation. ### Step 5: Determine the Genotypic Ratio in F2 Generation Using a Punnett square for the cross Rr x Rr, we get the following genotypes: - **RR** (homozygous dominant) - Red - **Rr** (heterozygous) - Red - **rr** (homozygous recessive) - White The genotypic ratio will be: - 1 RR : 2 Rr : 1 rr ### Step 6: Determine the Phenotypic Ratio in F2 Generation The phenotypic ratio corresponding to the genotypes is: - 3 Red (RR + Rr) : 1 White (rr) ### Step 7: Calculate the Number of Plants in F2 Generation Given that there are 120 plants in the F2 generation: - Total Red Flowers = (3/4) * 120 = 90 - Total White Flowers = (1/4) * 120 = 30 ### Conclusion In the F2 generation, out of 120 plants: - **90 plants will have non-uniform colored flowers (red shades)**. - **30 plants will have white flowers**. ### Final Answer The result would be: - 90 non-uniform colored flowers and 30 white flowers. ---
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